Plugin not working

Hi there! I just installed, activated, and configured your plugin and added some sub-page links to a page, but it’s just appearing as one long page… I’m at a loss as to how to troubleshoot this. No errors are appearing, and it seems that something is happening, in that the links are showing up in the source code having been transformed from, e.g. [nextpage title="What is a resurrection plant?"] to simply <!-- nextpage -->.

The content being displayed is drawn from a Custom Post Type — that’s the only variable I can think of that might be causing trouble — though I’m displaying the content with the usual the_content(); call. Before I installed the plugin, I tried out the built in pagination and that worked, though it was ugly. Any suggestions?